| /* |
| * This is the 1999 rewrite of IP Firewalling, aiming for kernel 2.3.x. |
| * |
| * Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling |
| * Copyright (C) 2000-2004 Netfilter Core Team <coreteam@netfilter.org> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| #include <linux/module.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netdevice.h> |
| #include <linux/skbuff.h> |
| #include <linux/slab.h> |
| #include <net/sock.h> |
| #include <net/route.h> |
| #include <linux/ip.h> |
| #include <net/ip.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Netfilter Core Team <coreteam@netfilter.org>"); |
| MODULE_DESCRIPTION("iptables mangle table"); |
| |
| #define MANGLE_VALID_HOOKS ((1 << NF_INET_PRE_ROUTING) | \ |
| (1 << NF_INET_LOCAL_IN) | \ |
| (1 << NF_INET_FORWARD) | \ |
| (1 << NF_INET_LOCAL_OUT) | \ |
| (1 << NF_INET_POST_ROUTING)) |
| |
| static const struct xt_table packet_mangler = { |
| .name = "mangle", |
| .valid_hooks = MANGLE_VALID_HOOKS, |
| .me = THIS_MODULE, |
| .af = NFPROTO_IPV4, |
| .priority = NF_IP_PRI_MANGLE, |
| }; |
| |
| static unsigned int |
| ipt_mangle_out(struct sk_buff *skb, const struct net_device *out) |
| { |
| unsigned int ret; |
| const struct iphdr *iph; |
| u_int8_t tos; |
| __be32 saddr, daddr; |
| u_int32_t mark; |
| int err; |
| |
| /* root is playing with raw sockets. */ |
| if (skb->len < sizeof(struct iphdr) || |
| ip_hdrlen(skb) < sizeof(struct iphdr)) |
| return NF_ACCEPT; |
| |
| /* Save things which could affect route */ |
| mark = skb->mark; |
| iph = ip_hdr(skb); |
| saddr = iph->saddr; |
| daddr = iph->daddr; |
| tos = iph->tos; |
| |
| ret = ipt_do_table(skb, NF_INET_LOCAL_OUT, NULL, out, |
| dev_net(out)->ipv4.iptable_mangle); |
| /* Reroute for ANY change. */ |
| if (ret != NF_DROP && ret != NF_STOLEN) { |
| iph = ip_hdr(skb); |
| |
| if (iph->saddr != saddr || |
| iph->daddr != daddr || |
| skb->mark != mark || |
| iph->tos != tos) { |
| err = ip_route_me_harder(skb, RTN_UNSPEC); |
| if (err < 0) |
| ret = NF_DROP_ERR(err); |
| } |
| } |
| |
| return ret; |
| } |
| |
| /* The work comes in here from netfilter.c. */ |
| static unsigned int |
| iptable_mangle_hook(unsigned int hook, |
| struct sk_buff *skb, |
| const struct net_device *in, |
| const struct net_device *out, |
| int (*okfn)(struct sk_buff *)) |
| { |
| if (hook == NF_INET_LOCAL_OUT) |
| return ipt_mangle_out(skb, out); |
| if (hook == NF_INET_POST_ROUTING) |
| return ipt_do_table(skb, hook, in, out, |
| dev_net(out)->ipv4.iptable_mangle); |
| /* PREROUTING/INPUT/FORWARD: */ |
| return ipt_do_table(skb, hook, in, out, |
| dev_net(in)->ipv4.iptable_mangle); |
| } |
| |
| static struct nf_hook_ops *mangle_ops __read_mostly; |
| |
| static int __net_init iptable_mangle_net_init(struct net *net) |
| { |
| struct ipt_replace *repl; |
| |
| repl = ipt_alloc_initial_table(&packet_mangler); |
| if (repl == NULL) |
| return -ENOMEM; |
| net->ipv4.iptable_mangle = |
| ipt_register_table(net, &packet_mangler, repl); |
| kfree(repl); |
| return PTR_RET(net->ipv4.iptable_mangle); |
| } |
| |
| static void __net_exit iptable_mangle_net_exit(struct net *net) |
| { |
| ipt_unregister_table(net, net->ipv4.iptable_mangle); |
| } |
| |
| static struct pernet_operations iptable_mangle_net_ops = { |
| .init = iptable_mangle_net_init, |
| .exit = iptable_mangle_net_exit, |
| }; |
| |
| static int __init iptable_mangle_init(void) |
| { |
| int ret; |
| |
| ret = register_pernet_subsys(&iptable_mangle_net_ops); |
| if (ret < 0) |
| return ret; |
| |
| /* Register hooks */ |
| mangle_ops = xt_hook_link(&packet_mangler, iptable_mangle_hook); |
| if (IS_ERR(mangle_ops)) { |
| ret = PTR_ERR(mangle_ops); |
| unregister_pernet_subsys(&iptable_mangle_net_ops); |
| } |
| |
| return ret; |
| } |
| |
| static void __exit iptable_mangle_fini(void) |
| { |
| xt_hook_unlink(&packet_mangler, mangle_ops); |
| unregister_pernet_subsys(&iptable_mangle_net_ops); |
| } |
| |
| module_init(iptable_mangle_init); |
| module_exit(iptable_mangle_fini); |